I think this point came up recently in another thread. The Indians produced modified forends for the SMLE later on in which the stock bolt keeper plate was dispensed with & a simple tie plate as per the No4 Mk1 forend was used. This also meant that the simplified (no squared off bit on the front end) No4 stock bolt could be employed. As mentioned above though, a Thackray type spring washer was required to tension it all.